SOAP, which stands for Simple Object Access Protocol, is a messaging protocol specification for exchanging structured information in the implementation of web services in computer networks. It uses XML Information Set for its message format and relies on application layer protocols, most often Hypertext Transfer Protocol (HTTP), for message negotiation and transmission.
SOAP provides a messaging framework that includes an envelope, which defines the message structure and how to process it, encoding rules for expressing instances of application-defined datatypes, and a convention for representing procedure calls and responses.